Magnetic temperature-control system



1,617,360 J. c. WOODSON v MAGNETIC TEMPERATURE CONTROL SYSTEM Feb. 15, 1927;

Filed April 24, 1925 ATTORNE awn/i 54 Patented Feb. 15, 1927.

7 UNITED STATES PATENT OFFICE.

JAMES C..WOODSON, EAST PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC 8; MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VA'IIA.

uAeNn'rIc TEMPERATURE-CONTROL SYSTEM.

Application filed April 24, 1925. vaerial No. 25,607.

My invention relates to electric furnaces, and particularly to temperature-limiting means'therefor. I I Oneobiect of my invention is to provide a relatively simple and compact means. comprising a minimum number of parts, for limiting the temperature of normally magnetic material being heated.

In practicing my invention. 1 provide an electric heating means for a furnace structure, an electromagnetic circuit-interrupting device therefor, and a core member of the same material as the mass to be heated. A portion of the core member is located in 5 heat-interchanging relation to the mass of material and has a movable member to open the magnetic circuit of the core member.

magnetizing coil is associated with the core member and is connected in series-circuit 9 relation to the trip coil of the circuit-interrupting device. 7

In the single sheet of drawings.

Figure 1 is a view of an electric furnace, in vertical section. comprising a device embodying myinvention, together with a schematic diagram of connection. and

Fig. 2 is a fragmentary view. in vertical section, taken on the line HH of Fig. 1. The numeral 11 indicates a furnace strum ture of any suitable or desired type. here shown schematically only as comprising a plurality of walls. a roof and a door structure. enclosing a furnace chamber 12 of any suitable or desired contour and. dimensions.

As the particular details of construction out the furnace constitute no part of my invention,no furtherfldetailed description thereof is believed necessary.-

-A mass 13 0f a normally magnetic material, such as steel or iron, is adapted to be located within the furnace chamber 12 and to be heated by suitable electric means, here indicated as a resistor member 14. The re sistor member 14 is illustrated schematically only, as it also constitutes no part of my invention and may be of any suitable or desired type usually employed in the art.

One of the walls of the furnace is provided with a suitable opening 15 extending .24 are mechanically secured, at one of their th'erethrough to receive a support and acircuit-interrupting means, to be described in detail.

A fixed magnetic core member 16 comprises a member of substantially U-shape that has associated therewith a magnetizing coil 17. The two terminals of the magnetizing coil 17 are connected, respectively, to one supply-circuit conductor 18 and to one terminal of a trip coil 19 ot a circuit-interrupting device 21, the other terminal of the coil 19 being connected to the other supply conductor 22. The circuit-interrupting device 21 is of the usual construction employed for such purposes, isconnectedin seriescircuit relation with the electric heating A means 14 and is of the type which will be moved to the open position upon an increase of current through thecoil 19.

Two relatively elongated members 23 and Tit respective ends, to the ends of the member 16 of ill-shape. An open magnetic circuit is provided by reason of the fact that the inner end portions of the members 23 and 24, that are located within the chamber 12 and in heat-interchanging relation relatively to'the mass 13 of material being heated, are bent at substantially right angles thereto. A. third member 25, that is preferably in the form of a straight bar, has its inner end 81 in operative engagement with the ends of the members 23 and 24, whereby the mag netic circuit thereof is normally closed.

A holder 26 is provided for the outer end Oillllle bar 25 and is pivotally supported 85 at 27. A spring 28 operatively engages the outer end of the holder 26 and tends to move the inner end of the member 25 out of engagement with the ends of the members 23 and 24. which action, however, is normally opposed and prevented by the magnetic flux produced by a current traversing the coil 17 which magnetic flux traverses theyoke or core member 16, the members 23 and 24 an a portion of the member 25.

While I have indicated a relatively large and solid mass 13 of normally magnetic material, it is to be understood that this is illustrative only and may comprise a plu-' rality of normally magnetic members, such as bars or rods. The members 23, 24 and 25 are of the same material as that constituting the mass 13 and, if relatively simple bars or plates are being heat treated, it is an easy matter to secure these members 23 to 25.

Upon energization ofthe heating means 14 and of the magnetizing coil 17 from the supply circuit conductors18 and 22, it 1s evident that the positions of the parts in Fig. 1 of the drawing are-the normal ones as long as the inner end portions of the members 23 to 25, inclusive, have not been heated to such an extent as to render them nonmagnetic, a condition which obtains when steel has been heated to a relatively high temperature, which temperature is that usually employed in heat-treating operations.

When the mass of material '13 has been heated to a temperature just beyond its recalescent point, the temperature of the members 23 to 25, inclusive, particularly of the end portions thereof that are in heat-1nter-changing operation relatively to the mass of material 13, will also be heated to substantially that temperature and will become substantially non-magnetic. The spring 28 will, therefore, when properly adjusted, be efi'ective to cause a turning movement of the member 25 away from the outer ends of the members 23 and-24, whereby the magnetic circuit is interrupted. This results in a sudden increase in the value 1 of the current traversing thecoil 17 and, with the proper adjustment of the overload circuit breaker 21, it will be actuated to its open position, whereby the electric heating means 14 will be deenergized and heating of the mass of material 13 willbe interrupted. The device embodying my invention is of particular value and particularly applicable to the heat treating of relatively simple forms of normally magnetic material, al though its use is not limited to the simple forms only, as it is possible to obtain magnetic materials 23 to 25. inclusive, that have substantially the same characteristics as that of the mass 13.

While I have shown the members 23 and 24 as of substantially L-shape, this is not an essential, as other cooperating shapes may be employed so long as a normally closed magnetic circuit is obtained, which may be interrupted as hereinbefore described.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof and all such modifications are intended to be covered by the-appended claims which are to be limited only by the prior art.

I claim. as my invention: a

1. The combination with an electric heating means, and a circuit-controlling device 1,e17,seo

therefor, of a magnetic core member, an energizing coil disposed thereon and connected to said circuit-controlling device, and means operatively associated with said core member for effecting an increase in the current traversing said coil at a predetermined temperature of. said means to actuate said circuitcontrolling device.

2. The combination with an electric heat ing means, and an electromagnetic circuitcontrolhng devlce therefor, of a normallyclosed magnetic circuit core member, a mag-' netizing coil therefor electricallyconnected to said circuit-controlling device, and means for effecting the opening of the m etic circuit of the core member at a re etermined temperature, whereby the increased current traversing the magnetizing co'il causes actuation of the circuit-interrupting device.

3. The combination with an electric heat- .ing means for heating a mass of normally magnetic material, a circuit-interrupting dc:

vice for said heating means and an actuating coil for said circuit-interrupting device, of a magnetic core member of the same material as that being heated, a coil for magnetizing said core member, connected in series circuit relation to said actuating coil, means for normally closing the magnetic circuit of said core member, said magnetic circuit closing means being subjected to the heat from the mass of material being heated,

and resilient means effective at a predetermined temperature of said magnetic circuit closing means to move the same to open the magnetic circuit of the core member, whereby the increased current traversing the actuating and magnetizing coils effects the actuation of the circuit-interrupting device.

4. In an electric furnace, the combination with a furnace chamber, and an electric heating means therein for heat treating material 5.- The combination with anelectric heat:

ing means. and a normally magnetic core member, of an electromagnetic circuit-interrupting device for controlling the energization of the heating means, and. an electric coil member operatively associated with, and controlled by, the normally magnetic core member for effecting actuation of the circuit- -interrupting device at a predetermined temperature of thecore member,

6. The combination with an electric. heating means for heating a mass of normally magnetic material, and a core member of the deenergization of the heating element when vsame material as the mass being heated, of a the core member becomeenon-magnetic. magnetizing coil for said core member, and. 'In testimony whereof, Ifhave hereunto 10 an electromagnetic circuit-interrupt ng desubscribed my name this 20th day of April, .15. Vice for controlling the 'ener fization of said 1925. r v heating-means an electrical y connected to the magnetizing coil and efiective to cause. JAMES C. WQODSON. 

